Lifestyle health and risk Flashcards
what is a polar molecule?
molecule that contains both positive and negative charge
what type of molecule is water?
polar molecule
which part of water is more negative?
oxygen
which part of water is more positive?
hydrogen
what holds multiple water molecules together?
weak hydrogen bonds
what is a solvent?
a liquid in which things dissolve in
why does water form droplets?
cohesion, hydrogen bonds keep water molecules attracted to eachother
why is water a good solvent?
the hydrogen attracts negative ions, and the oxygen attracts positive ions
what is cohesion?
water being attracted to water
what is adhesion?
water being attracted to surfaces
what type of molecules are hydrophillic?
polar
what type of molecules are hydrophobic?
non-polar
why is it so hard to raise waters temperature?
alot of energy is needed to break the hydrogen bonds between water molecule
why do animals stay in water?
to maintain a cool temp and stop enzymes denaturing
what does buffer mean?
resistant to change
what is water potential?
the ability of water to move
how does water always move, relative to water potential?
from high water potential to low water potential
why is water polar?
the electrons spends more time near the oxygen.
why is water less dense as a solid?
hydrogen bonds form when water is below 4 C and fix the polar molecules slightly further apart than in liquid state.
what chemical structure is ice?
giant, rigid but open structure with every oxygen atom at the centre of a tetrahedral arrangement of hydrogen atoms
why is water so important for life?
acts as a medium for chemical reactions and also helps transport dissolved compounds into and out of cells
what is capillary action?
the process by which water can rise up a narrow tube against gravity
why is the fact that ice floats so important for aquatic life?
ice forms an insulating layer above the water below.
name 2 examples of disaccharides?
- maltose
- sucrose
name 2 examples of monosaccharides?
- glucose
- fructose
name 2 examples of polysaccharides?
- glycogen
- starch
what is the generic formula for carbohydrates?
C:2H:0
what type of monosaccharide is glucose?
hexose monosaccharide
what is the difference between alpha and beta glucose?
in alpha, the hydroxyl group is below the ring plane
what happens when 2 alpha glucose are close enough to eachother?
their hydroxyl groups react, a bond is formed and H2O is lost
what type of reaction occurs between 2 alpha glucoses?
condensation reaction
what type of bond is formed between 2 alpha glucose?
1 - 4 glyosidic bond
what type of bond is a 1-4 glycosidic bond?
covalent bond
why is amylose less soluble than other sugars?
the angle of the bond means that this long chain of glucose twists which is further stabilised by hydrogen bonding within the molecule.
what 2 polysaccharides make starch?
- amylose
- amylopectin
how is amylose formed?
many alpha glucose molecules joined together by only 1-4 glycosidic bonds
how is amylopectins formation different than amyloses?
there are also some glycosidic bonds between carbon 1 and carbon 6 atoms
what does amylopectins 1-6 glycosidic bonds cause?
gives it a branch structure, with the 1-6 branching points being every 25 glucose subunits
what is starch used in?
plants
what is glycogen used in?
animals and fungi
why is glycogen more compact than starch?
forms more branches than amylopectin
why is branching needed for animals?
- more compact
- leaves many free ends where glucose molecules can be added or removed, speeding up the process
what are the 3 main properties of glycogen and amylopectin?
- insoluble
- branched
- compact
what is the reverse of a condensation reaction?
hydrolysis reaction
why are beta glucose molecules not able to join together like alpha glucose molecules?
there hydroxyl groups on carbon 1 and 4 are to far apart to react
how do beta glucose molecules join together?
if an alternate glucose molecule is turned upside down
what is a polysaccharide formed from beta glucose molecules called and described as?
a straight chain molecule called cellulose
is cellulose branched?
no
what do hydrogen bonds between cellulose
molecules form?
microfibrilis
what do microfibrilis form?
macrofibrilis and then they form fibres
what are cellulose fibres used for?
cell walls
what are the characteristics of cellulose fibres?
- strong
- insolule
name 5 uses of lipids?
- source of energy
- energy storage
- biological membranes
- insulation
- waterproof
- protective cushioning for organs
- steroid hormones
name 4 properties of lipids?
- twice the energy of carbohydrates
- made of only C,H,O
- not polymers
- insoluble in water
- soluble in organic solvents like ethanol
- energy dense
what are triglycerides made of?
1 molecule of glycerol and 3 fatty acids bonded together
how are triglycerides synthesised?
by the formation of an ester bond between each fatty acid and the glycerol
how is each ester bond in a triglyceride formed?
a condensation reaction
what is esterification?
the process in which triglycerides are synthesised
how are ester bonds broken down?
a hydrolysis reaction
what is the purpose of cholesterol?
stabilise the membrane
name the characteristics of cholesterol heads?
polar and hydrophillic
name the characteristics of cholesterol tails?
non-polar and hydrophobic
what are HDL’s and LDL’s examples of?
lipoprotiens
what do HDL’s do?
carries cholesterol to liver
what do LDL’s do?
carries cholesterol to cells
what makes cholesterol?
the liver
what does cholesterol do to stabilize membranes?
binds the phospholipids together using its opposite head and tail
what is cholesterol?
a steroid, as its made of carbon rings
why does cholesterol form lipoprotiens?
so it can be transported in blood
how does cholesterol regulate the fluidity of membranes?
- keeps membranes fluid at low temperatures
- stopping them becoming too fluid at high temperatures
what does transmembrane mean?
spans the width of the phospholipid bilayer
what type of substances can easily pass through a phospholipid bilayer?
small non-polar substances and water
what are receptors made of?
glycoprotiens
what type of substances can pass through protein channels?
ions/polar substances
what makes a glycoprotein?
protein + carbohydrate group
what are peripheral proteins?
receptors
what do golgis do?
modify proteins
what do vesicles do?
transfer proteins
what do channel proteins do?
allow certain proteins through the phospholipid bilayer
are channel proteins passive or active?
passive
what do carrier proteins do?
transport ions or molecules by active transport, passive diffusion or facilitated diffusion
what can carrier proteins do to substances that they transport?
change their conformity (shape)
what molecules can pass through membranes?
- water
- small molecules
- lipid-soluble molecules
name 4 features of all cytosis?
- moves large quantities
- fusing and pinching of membranes
- actives process
- forming and moving vesicles
what happens in endocytosis?
a solid substance is taken into the cell by the infolding of a membrane
what happens in exocytosis?
a vesicle fuses with the membrane to release its contents
what is pinocytosis?
endocytosis with liquids
what does hypotonic mean?
more water than solute
what does hypertonic mean?
more solute then water
what does isotonic mean?
equal water and solute
how many forms of RNA exist?
3
name 3 differences in RNA from DNA?
- single stranded
- the base uracil is found instead of thymine
- the sugar molecule is ribose instead of deoxyribose
what are the 3 forms of RNA?
- mRNA
- tRNA
- rRNA
name 3 features of mRNA?
- made in the nucleus
- 3 adjacent bases = a codon
- it carries the genetic code from the nucleus to the cytoplasm, where its used to make a protein during translation
name 3 features of tRNA?
- found in the cytoplasm
- has an amino acid binding site at one end and an anticodon at the other
- carries the amino acids for proteins to the ribosomes during translation
name 2 features of rRNA?
- forms the 2 subunits in a ribosome
- helps to catalyse the formation of peptide bonds between amino acids
what 2 phases converts DNA into proteins?
- translation
- transcription
what does transcription mean?
to copy the DNA
what does translation mean?
converting to another form
what is the first phase of DNA replication?
transcription
what happens in transcription? (6 steps)
- double helix unzips by DNA helicase as the hydrogen bonds between base pairs break
- so the 2 polynucleotide strands separate
- the sense strand acts as a template, free RNA nucleotides form complementary base pairs to the exposed bases.
- RNA polymerase forms sugar-phosphate bonds between nucleotides
- The mRNA detaches from the sense strand
- The two DNA strands join back together and The DNA molecules winds back up into a helix
what is a transcription factor?
special proteins that recognise specific sequences of DNA in promoter regions
where does translation occur?
ribosomes
what is the main job of tRNA in translation?
to carry specific, individual, amino acids
what is the main job of rRNA in translation?
stabilises protein synthesis & helps catalyse the reaction
how does mRNA move out of the nucleus?
through a nuclear pore
name the 7 stages of translation?
- the mRNA attaches to a ribosome, and tRNA carries an amino acid to the ribosome
- a tRNA with an anticodon complementary to the first codon on the mRNA attaches to the molecule
- a second tRNA molecule attaches to the next codon in the same way
- rRNA catalyses the formation of a peptide bond between the amino acids attached to the tRNA, the first tRNA moves away
- an third tRNA binds to the next codon, its amino acid binds, then it moves away
- this process continues, producing a polypeptide chain until a stop codon is reached
- the chain moves away from the ribosome and translation is complete
name the 3 parts of a general amino acid formula?
- variable R group
- amino group (NH2)
- carboxyl group (COOH)
what is a histone?
positively charged protiens
how are chromosomes formed?
- DNA wraps around histones to form nucleosomes
- these clusters coil and supercoil to form chromosomess
what is a centromere?
centre of a chromosome
what are the 4 phases of mitosis?
- prophase
- metaphase
- anaphase
- telophase
what occurs in prophase?
- chromosomes become visible
- nuclear membrane breaks down
- centrioles move to opposite sides
- spindles fibres develop from centrioles
what occurs in metaphase?
- spindle fibres attach to the centromeres
- chromatids line up in the centre
what occurs in anaphase?
- spindle fibres pull chromatids apart
- chromatids move to opposite sides
- mitochondria surround the spindle fibres, providing energy
what occurs in telophase?
- nuclear membrane forms around chromosomes at opposite ends
- chromosomes become indistinct
- spindle fibres disapear
what is a mutation?
random change in sequence of bases
what are the 6 types of asexual reproduction?
- binary fission
- producing spores
- regeneration
- producing buds
- propagation
- parthenogenesis
what is the definition of growth?
permanent increase in number of cells or size and mass
what is the definition of assimilation?
incorporating new materials into cells
what is independant assortment?
chromosomes from either parent are distributed randomly to different sides of the equator
what is crossing over?
chromatids can tangle and break off then combine with new chromatids
what is a homologous pair?
chromatids attached, joined by a centromere
when does random fusion of gametes occur?
fertilization
what is an autosome?
non-sex chromosome
what is co-dominance?
2 alleles with equal influence
what is an allele?
versions of a gene
what is a locus?
position of a gene on a particular autosome
how does gene locus affect variation?
2 or more genes with the same locus cross over
what is ficks law?
(SA X concentration difference) / membrane thickness
what is DNA?
the code for protiens
what is a base?
compound that joins 2 strands of DNA
what is a gene?
sub-section of a chromosome
what is a genome?
all genetic material in an organism
how are 2 DNA strands joined together?
one strand is flipped upside down so they are parallel and can join at bases
how are nucleotides joined?
by phosphodiester bonds in a condensation reaction
what bases are purines?
A + G
what bases are pyrimidines?
T + C + U
features of purines?
- 3 bonds
- bigger than pyrimidines
features of pyrimidines?
- 2 bonds
- smaller than purines
name 3 features of RNA?
- ribose sugar
- 1 strand
- U over T
what does DNA helicase do?
unzips DNA
what does DNA polymerase do?
copies DNA
what does DNA ligase do?
rejoins DNA strands
what is a primary protien structure?
the order of amino acids (peptide bonds)
what is a secondary protien structure?
alpha helices and beta pleated sheets (hydrogen bonds)
what is a tertiary protien structure?
3D folding of amino acids and subunits, involves bonds ionic + hydrogen + disulphide bridges
what is quaternary protien structure?
multiple tertiary shapes
what is spermatogenesis?
process that forms sperm in mammals
what is oogenesis?
process that forms eggs in mammals
what is the zona palosida?
part on cell membrane on an egg cell that hardens
name 2 processes that prevent polyspermy?
- ion channels open then close
- cortical reaction = hardens zona palosida
what is semi conservative DNA replication?
- DNA strand is unzipped
- each strand acts as a template for a new strand
- original strand and new strand join together
why is semi conservative DNA replication called semi conservative?
half of the original DNA molecule is kept (conserved)
name the 4 steps of messelson and stahl’s experiment?
- bacteria were grown in a broth containing heavy nitrogen
- a sample of DNA was taken and spun in a centrifuge
- the bacteria containing only heavy nitrogen DNA were taken out and added to a light nitrogen broth
- removed after 1 round of replication and centrifuge
how many lines does semi-conservative DNA replication form after 1 generation?
1, a mix of both heavy and light nitrogen
what is the function of mucus?
to trap bacteria
what happens if mucus is too thick?
it cant be dislodged so bacteria builds up, causing infection
what happens if mucus is too runny?
it cant trap bacteria
what does cystic fibrosis cause?
gene mutation in the CFTR protein, causing to not open
describe the 5 steps that occur in order to correct mucus that is too runny?
1) Na pump pumps out Na from epithelial cell into tissue fluid
2) causing a low Na conc. in the cell
3) so Na from mucus flows into cell
4) due to electrochemical gradient, Cl ions flow into tissue fluid from mucus
5) creating low water potential in the tissue fluid, so water flows in from the mucus
describe the 6 steps that occur in order to correct mucus that is too thick?
1) Cl pump pumps in Cl ions from tissue fluid
2) when Cl conc. is high, CFFTR protein opens
3) Cl flows from cell into mucus
4) Na channel closes to keep Na from leaving mucus
5) Na from tissue fluid enters mucus, due to electrochemical gradient
6) lowering water potential in mucus, so water from tissue fluid enters mucus
